Dishwashing apparatus



ug 14, 1962 D. A. MEEKER ETAI. 3,049,391

DISHWASHING APPARATUS Filed May l2, 1961 5 Sheets-Sheet 1 INVENToRs l0 DAVID A. MEEKER a y GERALD B. Fox

AT ToRNgYs l Aug. 14, 1962 D. A. MEr-:KER ETAL DISHWASHING APPARATUS 5 Sheets-Sheet 2 Filed May 12, 1961 INVENToRS DAV1D A. MEEKER at By GERALD B. FOX

ATTORNEYS Aug. 14, 1962 D. A. MEEKER ETAL DIsHwAsHING APPARATUS 5 Sheets-Sheet 5 Filed May 12, 1961 DAVID A. MEEKER a GERALD B. Fox www4/?? FIG-lO ATTORNEYS Aug 14, 1962 D. A. MEEKER ETAL 3,049,391

DIsHwAsHING APPARATUS Filed May l2, 1961 5 Sheets-$11991'l 4 FIG-12 34 230 FIG-11 also 240 250 AA T 240 "22e l 48A ."245 s 243 l 235 ,"237 m 'NMI 55@ "wlnlllwm i 2z7.\ 50 n ,-237 1, i :zzz

|*5 l5 MT +I4 `z29 225x 248 INV EN TORS DAVID A. MEEKER 6 BY GERALD B. FOX

3 WMMA@ ATTORNEYS Aug. 14, 1962 D. A. MEEKER ETAL 3,049,391

DISHWASHING APPARATUS Filed May l2, 1961 5 Sheets-Sheet 5 FIG-16 IN V EN TORS DAVID A. MEEKER 8 By GERALD B. FOX

ATTORNEYS United States Patent O 3,049,391 DISHWASHiNG APPARATUS David A'. Meeker and Gerald B. Fox, Troy,l Ohio, as-

signors to The Hobart Manufacturing Company, Troy, Ohio, a corporation of Ohio Filed May 12, 1961, Ser. No. 109,578 13 Claims. (1. S12-272) The present invention relates to dishwashing apparatus, and particularly to improvements in dishwashing machines having a chamber with one or more vertically movable doors providing access to the chamber for the loading and unloading7 of articles to be cleansed, especially dishes, trays, and the like carried in supporting racks.

The present invention has for its primary objective an improved control mechanism which governs the opening and closing of the door or doors of the machine, including a simple arrangement which will counterbalance the door in raised open position while not interfering with maintaining the door in closed position. In actual practice there are two most common types of constructions in machines of this nature, hereinafter referred to as straight through machines and corner machines. This language is descriptive of the manner in which the machine is installed and used, since in the straight through machine it is usual to have entrance and exit doors at opposite sides of the machine, preferably opening and closing together, whereby the loaded racks of dishes can be pushed onto supporting rails in the chamber through the entrance door and the rack of cleansed dishes can be pushed or pulled through the opposite exit door onto a table or the like. The ilow of the articles to be cleansed is thus straight through the machine from one side to the other.

In the corner machine, which employs the same washing and rinsing apparatus, the same general cabinet structure, and which in fact 'has most parts in common with the straight throng machine, the chamber is placed in a corner of the room or against other equipment, and the entrance and exit doors are on adjacent sides such that the ilow of articles and racks is through the machine at right angles. Again, these doors on adjacent sides are preferably raised and lowered simultaneously by the same mechanism.

The principal object of this invention, as noted above, is the provision of a novel control and operating mechanism for such doors of the dishwashing machine, the principles of such mechanism being applicable to either type of machine, and being capable of' execution by mechanism which is uncomplicated in construction and thus durable, inexpensive to manufacture, and requiring practically no maintenance.

Another object of the invention is to provide such a door control mechanism which is constructed within the established dimensional confines of the machine, and which thus does not interfere with the installation of the machine in space presently allocated to machines of this type.

A further object of this invention is to provide a novel door operating and counterbalancing mechanism for dishwashing machines in which a coil tension spring is elective to maintain the door or doors in raised open position, while not interfering with the placement and continued positioning of the doors in lowered closed position.

An additional object of this invention is to provide such a control mechanism including a generally U-shaped lever pivotally mounted on the machine such that it provides control arms extending adjacent to the door or doors of the machine and a central or operating portion on the opposite side of the pivot axis, and having a pivotal connection through a balance link with an elongated coil tension spring, the arrangement being such that the force exerted by the spring is directed closer to the pivot axis "ice when the doors are closed than when they are opened, providing an increased moment from the spring force in the open position suicient-to hold the doors inf-the open position.

Another object of the invention is to provide such a'- control mechanism wherein either of the control arms provides a convenient operating handle which can be grasped by the operator to raise and lower the doors'V simultaneously.

Another feature of this invention relates to the provi-l sion of a dishwashing machine of the type described above having a vertically enlargedchamber. CertainV articles are considerably oversized, and in particular one article which requires cleansing, and which cannot be accommodated in a standard size machine, is a so-called hotel tray. This is a metal tray used for carrying aV number of servings, and the trays vgenerally are elliptical in form, having a major diameter of between 27y and` 28 inches and a minor diameter in the order ofI 22` to 23 inches. It is the larger dimension that exceeds the normal or standard interior size of machines of this kind In accordance with the invention a machine isp'rovid'ed having a chamber elongated vertically suicient to accommodate articles of this type wit-h the larger dimension arranged vertically, for example by stacking a number of such trays in a rack. The machine embodies the novel door control and operating mechanism as set forth above, and in addition the doors are provided with auxiliary panels hinged to their lower ends and movable outwardly from the main portion of the doors to provide a larger opening to the interior of the machine. When the oversized articles are not being washed this machine can be operated in the normal manner, with the auxiliary door panels merely hanging vertically from the main portion of each door.

Therefore, it is another important object of this invention to provide a novel dishwashing machine capable of receiving and cleansing oversized articles such as trays and the like including auxiliary movable panels on the doors which can be operated independently of the doors to provide a larger access opening when admitting oversized articles to the machine.

A further object is to provide such a machine in which the auxiliary door panels are automatically opened and closed during opening and closing of the main doors.

Another object of the invention is to provide such an arrangement for 'lan oversized machine wherein the door `control mechanism includes -an interlock arrangement operable to `align the auxiliary door panels properly when the doors are moved to their closed position, assuring' proper sealing of lthe washing chamber before the washing Yand rinsing spray mechanism is actuated.

Other objectsand advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawing- FIG, 1 is a side elevational View, with certain parts broken away, showing one type of dishwashing machine embodying the n'ovel door control and operatingV mechamsm;

FIG. 2 is a front view of the machine shown in FIG. 1, as viewed from the right of FIG. l

FIG. 3 is an enlarged detail section taken on line 3--3 of FIG. 1 through la portion of the corner of the inachin'e, showing the manner in which the doors are mounted for vertical movement; p

yFIG. 4 is a view from the top of FIG. l, sho-wing the general outline `of the door control mechanism;

FIG. Suis a view similar to FIG. l, showing the limits of movement of the doors and control mechanism, with the device shown in open position in full lines and" in closed position by the dotted lines;

FIG. 6 is an enlarged detail section taken on line 6 6 in FIG.

FIG. 7 is an enlarged sectional View of the pivot mounting of the control lever, taken online 7-7 in FIG. 5

FIG. 8 is an enlarged detail section taken on line 8 8 in FIG. 4;

FIGS. 9 and 10 are, respectively, top plan and partial side elevation views of a modified form of the invention, illustrating the application of -the control mechanism to a machine having adjacent entrance and exist doors;

FIG. 1l is a side view similar to FIG. 1, showing another modified form of the invention, incorporating a vertically enlarged chamber, and movable auxiliary door panels;

FIG. l2 is a View similar to FIG. 11 with the door in its open position and the auxiliary panel raised;

FIG. 13 is a View from the rear of the machine shown in FIGS. l1 and 12, in other words looking from the left of such figures, with the doors in raised position and with one of the auxiliary door panels raised, illustrating the manner in which oversize articles can be loaded and unloaded;

FIG. 14 is an enlarged detail section taken on line 14-14 in FIG. 1l, showing the relationship `between the auxiliary door panels and the main door track;

FIG. l5 is an enlarged detail section taken on line 15-15 in FIG. 11, showing the interlock arrangement between the auxiliary door panel and the control arm;

FIGS. 16 and 17 are enlarged sectional views of a modified arrangement by which the auxiliary door panels are raised and lowered automatically;

FIG. 18 is a sectional view on line 18-18 of FIG. 17;

FIG. 19 is a View showing -a similar modified form to that shown in FIGS. 16-18; and

FIG. 2O is an enlarged detail section of lthe hinging construction for the auxiliary door panels.

Referring to the drawings, and particularly to FIGS. 1-8, the dishwashing machine includes a base section indicated by the general reference numeral 10, mounted on legs 11. This section of the machine includes a tank for washing liquid, la pump for recirculating the wash liquid from the tank through the wash arms 12, a drive motor for such pump, and suitable plumbing connections for supplying rinse liquid to -the lower spray head 13 and the upper spray head 14. Details of these devices are fully illustrated and described in Johnston Patent No. 2,071,- 036, issued February 16, 1937, to the assignee of this application, :and in Fox Patent No. 2,286,203, issued lune 16, 1942, also to the assignee of this application. In some instances it is desirable to include a heater for the liquid in the tank, and for this purpose it is cutomary to provide a flue construction 15 (FIGS. l and 4) at the rear of the machine to exhaust fumes from a suitable gas heater.

The cleansing chamber of the machine is the general area between the aforementioned spray heads, and tracks 17 are mounted in this chamber providing support for the dish carrying racks which are loaded manually thereinto. Obviously, with a machine as shown in FIGS. 1-8, either side may be considered the entrance and the opposite side the exit, this being the straight through embodiment of the machine las mentioned previously. The chamber is enclosed by a back wall 20 and a top 22, and at the front corners of the chamber, projecting up from the base structure 10, there are elongated angle pieces (FIG. 3) which form the mountings for outer track defining corner pieces or angles 26. These parts are secured in predetermined relation by screw fasteners 27, with spacers 28 therebetween maintaining the desired spacing. It will be noted from FIG. 6 that the rear wall 20 of the machine is formed inward at 29 and is also connected to an outer angle member 26 at each of the rear corners to form similar tracks.

These tracks form mountings for side doors 30 and 32, and also in this particular embodiment for a front access door 33. The doors 30 and 32 are designed to move vertically and simultaneously within the tracks, and are guided for this purpose by turned edges 34 which maintain the doors in the tracks during such movement. The front access door 33 also is provided with such guiding edge portions 34, but it has a separate handle 35 for manual grasping to move the access door independently. Normally it is opened only for inspection, cleaning, and other maintenance.

The control mechanism provided by this invention for simultaneous opening and closing of the doors 30 and 32, and also for counterbalancing these doors to hold them in the raised open position, is constituted by an operating lever indicated by the general reference numeral f 40. This lever, as can be seen in FIG. 4, is of generally U-shape, and thus includes control arms 42 and 43, preferably parallel, which extend adjacent these doors, and preferably terminating short of the front edge of the doors, as shown in FIGS. l and 5, such that the arms do not protrude beyond the front of the machine. Across the back of the machine the base or central drive arm portion 45 of the control lever provides a drive arm to which the force is applied for counterbalancing the doors.

The pivotal mounting of the control lever is shown in detail in FIGS. 4, 6 and 7. The mounting includes an L-shaped bracket which is conformed to the exterior configuration of the corner angle 26. There are two such brackets 50, one at each rear corner of the machine as shown in FIG. 4. Since the shapes of the bracket and of the angle member 26 are complementary, they may be secured together by a single mounting screw 52, and when this screw is tightened, the bracket is securely fixed to the angle. A stud 53 (FIG. 7) extends outwardly from bracket 50, and is fixed thereto as by welding at 54. Around this stud there is a sleeve bearing 55, for example in the form of a tube of synthetic resinous material.

The stud 53 and bearing sleeve 55 extend through an aperture 58 in the control arm 40, and also into an outer knob 60, being received in a bore 62 within the knob. In turn, the lever 40 extends through a cross bore 63 in the knob.

The manner of assembly of these units is somewhat unique. This is done by placing the knobs 60 over the control lever 40, aligning the bore 62 with the hole 58 through the lever, and then inserting the studs 52 with the bearing sleeves thereon into the aligned holes. The assembled control lever and pivot mounting brackets can then be slipped over the rear angle pieces 26 at the corners of the machine and the entire mechanism secured t0 the machine merely by insertion of the two retaining screws 52.

Accordingly, the studs 53 of each pivot mounting being aligned across the machine, defining a pivot axis, and the control arms 42 and 43, which can be considered as those portions of lever 40 extending forward of the pivot axis, are arranged to swing about such pivot axis in one direction, while the drive arm portion 45 swings in the opposite direction. The direction of rotation of these parts with respect to the pivot axis is of course the same in either direction, but when a point on the control arm is moving downward a point on the drive arm is moving upward.

Control links 62 and 63 are connected between the arms 42 and 43 and the doors 30 and 32 respectively for accommodating swinging movement of the arms to the linear movement of the doors. Thus, link 62 has a pivotal connection 64 to arm 42 and a separate pivotal connection 65 to a point on door 30. Preferably, the connection 64 is spaced inwardly somewhat from the end of the control arm and the free end of the arm thus forms a convenient handle for grasping by the operator. Simi larly, link 63 has a pivotal connection 67 with the arm 43 and a pivotal connection 68 with a point on door 32. These doors, therefore, are arranged for simultaneous raising and lowering in response to swinging motion -rof the control lever, land* the pivoting control lever mechanism forms a simple and effective operator for simultaneous moving of the entrance and exit doors of the machine.

It is desirable to have the doors maintained in their raised' position, such as shown in FIG. 5, without the need of external force applied by the operator. This frees the operator to load ard unload the racks from the machine with both hands. The control mechanism provided by this invention also affords a reliable and maintenance free counterbalance arrangement. The compensating force is preferably provided by one or more relatively long coil tension springs 70. The lower end of the spring or springs 70 is anchored to a fixed point on the machine, as by the eye bolt 72 shown at the lower end of the spring in FIG. l. Since, as noted previously, the usual practice is to provide the flue on the machine, or to allow space for it, a convenient arrangement has` been found in locating the spring or springs on opposite sides of this flue, as shown in FIG. 4 particularly, and the entire structure can be enclosed within a suitable housing piece 74. This piece not only encloses the springs but also provides some insulating space between adjacent walls and the fiue 15.

The spring or springs 70 are relatively long and are preferably ofthe type known in the art as low-rate springs. Thus, the effective force exerted by such springs when they are stretched a relatively short 4distance in comparison to their length can be considered as essentially constant. Any other apparatus for exerting a substantially constant compensating force can be used within the concept of the invention, but the long low-rate coil tension springs illustrated and described have been found effective and economical for this purpose.

The compensating force exerted by the spring or springs is transferred to the central portion or drive arm 45 of the operating lever through a balance link 75, there being one such link for each spring used. This link may be merely an elongated rod having hooked por-tions at its opposite ends, as shown particularly in FIGS. l and 5. At its lower end the balance link isy hooked or otherwise connected to spring 70, and at its upper end there is a pivotal connection with the central portion 45 of the control lever. This connection is preferably in the form of a hook shaped piece `80, in the general form of a question mark as shown in FIG. 8, fwhich is engaged at 82 with the upper end of balance link 75, and which includes a plurality of bearing pieces y83, for example plugs o-r inserts of synthetic resin material, engaging the surface of .the arm 45. In order to avoid shifting of the part 8f) on the arm portion `45, a locating pin 84 is inserted through the arm, and normally the member 80 rests against the side of the pin, free to rotate about Ithe arm portion 45.

The relationship of the parts is such that the turning moment exerted by the spring means through the balance link 75 is increased as the lever 40 is swung in a direction to raise doors and 3'2. It is seen in F'IG. 5 that with the doors lowered, in the dotted line position, the balance link 75 is fairly close Ito the pivot axis of the control lever, and as the doors raise the pivotal connection provided by the part 8'0 rotates in the opposite direction to movement of the central lever portion or arm about the pivot axis, thus carrying ythe balance link 75 outwardly from the lever pivot axis and effectively increasing the component of the 4force from spring 70 which acts upon the system. By choosing a spring or springs of the proper rate and force, and utilizing this change in turning moment, it is possible to have the force of the springs sufficient to maintain the doors in their raised position While being ineffective to move the doors from their closed position without application of an external force to the control mechanism by the operator. In other words, the doors will stay closed, but once the operator grasps one of the control 6 arms and raises the doors, they will remain in the open position.

FIGS. 9 and l() show the manner in which the present invention is adapted to a corner type of machine, which was described briefly at the outset of this specification. Many of the parts are identical, or quite similar, to the parts described in connection with the aforementioned embodiment. Therefore, the same reference numerals in the one hundred series are applied to similar or identical parts.

The machine includes a base 110, portions of which are shown in FIG. l0, and the back 12)` and top .122 of the machine cooperate with the doors and 132, and the fixed side wall 133, to define the `washing chamber. The outer corner pieces or angles 126 are shown at each corner of the machine, and it will be noted that those of the corner pieces which are adjacent to the movable doors 130 and 132 include inwardly turned edges cooperating with the outwardly turned edges 134 on these doors to form guide tracks. The control lever includes arms 142 and 143 which extend downwardly adjacent to the doors 130 and 132 respectively. These arms are also curved around the corners of the machine and extend upwardly at an angle to the central or drive arm portion 145, and the extent of these arms, which are preferably formed from a single -rod or tube, is determined by the pivot axis which is defined by the mounting studs 153 on the respective arms.

These studs include an inner segment 154 of reduced diameter, received in a bearing sleeve 155 which is in turn mounted within a stationary socket 157. The socket extends from a mounting flange 158, and these flanges are secured to the walls 126 and 133 in aligned relation, as shown particularly in FIG. 9, to define a pivot axis through the corner of the machine opposite to that corner at which the doors 13G and 132 adjoin.

A compensating spring is mounted within the housing 174 at the rear of the machine, and anchored at its lower end in the same manner as previously described, and shown in FIG. 1. The upper end of this spring is secured to the balance link 175, which in turn extends upwardly to a pivotal connection with a bracket or arm 182 fixed to the drive arm portion 145. In this configuration, the balance link includes an offset section 176 which provides for clearance between this link and the central arm portion 145 of the control lever to provide for movement of the balance link away from the pi-vot axis as the doors are raised. The control and counterbalancing is achieved in the same manner by this mechanism, with the single compensating spring 17) being selected of such force and rate that it will maintain the doors in raised open position, but will be ineffective to move the doors from the lowered or closed position without application of some external yforce by the operator.

FIGS. 11-15 illustrate a further modification of the invention, and again a number of like or simila-r parts are designated by similar references, where possible, here in the two hundred series. At the outset of this specification, there is an explanation of the requirements for a machine capable of washing oversize articles. 'I'he most typical example is the hotel trays referred to at that time.

The machine, therefore, is provided with a vertically enlarged chamber capable of receiving these oversized articles. Thus, referring to FIGS. 11, 12 and 13, the base structure 210 of the machine provides a support for the chamber and the spray apparatus (not shown), and the chamber includes a back wall 220 and a top 222 which cooperate, in this configuration, with a fixed front wall shown generally at 233 to define the elongated chamber. At the corners are the same type of track constructions, including the inturned parts 229 of rear wall 220 (FIG. 14) and the outer angle members 226 fixed thereon and forming the guide tracks for the main door panels 230` and 232. At the front corners there are the internal track forming angles 225 (FIGS. l2 and 13). These door panels include the outwardly turned edges 234 which are received in the tracks, thus guiding the doors for vertical movement.

Door panels 230 and 232 cover, in their lowered position shown in FIG. ll, only a fraction of the total exit and entrance openings to the chamber of the machine, and the remainder of these openings is covered by auxiliary door panels 235 and 236, having hinge connections 237 to the main door panels 230 and 232, respectively. The auxiliary door panels include guiding and bathing members 23S at their opposite sides (FIG. 14) and the hinge connections preferably are fixed to the lower edges of the main door panels somewhat above the turned back lower edge of the main door panel, particularly as shown in FIG. 19, forming a `baiing arrangement which essentially prevents leakage of the liquid around the auxiliary door panels when they are closed.

In one embodiment of the invention the auxiliary door panels are controlled manually, and for this purpose handles 245 are provided on each auxiliary panel `for grasping `by the operator, who can swing the auxiliary panels to their raised position, shown particularly in FIG. 13, providing an enlarged entrance or exit opening to the chamber of the machine.

Since the auxiliary panels swing outwardly in this fashion, they must of course be less in width than the track dimension for the main door panels, and the auxiliary panels thus terminate at their opposite sides short of the outer guiding or corner and track forming angles 226. This relationship is shown on a larger scale in FIG. 14. Accordingly, since the lower end 239 of the auxiliary panels descends beyond the edge of the base 210, particularly as shown in FIG. 1l, to form a bafiiing arrangement at this point, it is necessary to assure the complete closing movement of the auxiliary panels against the interior parts before the doors are fully closed.

For this purpose, the arms 242 and 243 of the control lever 240 are extended and curved, as shown particularly in FIG. 1l, to project when lowered across the hinge line between the main and auxiliary door panels on each side. These extended arm portions 247, cooperate with a cam plate 248 xed to the auxiliary door panels in such relationship that as the control lever is swung to close the doors, the end control arm portions 247 will pass over the cam plates on each side and force the auxiliary door panels inward to assure that they will align with the main door panels before the doors are fully lowered. If desired, a convenient grip 250 can be attached to the arm extension part 247 for grasping by the operator, and by locating the grip in this manner, the operators hands will be placed away from possible pinching between the cam plate and the extended arm portion as he manipulates the door control mechanism.

In other respects, the control mechanism for the doors operates in the same manner as previously described, and accordingly further detailed description is unnecessary. It might `be noted, however, that the machine can operate with conventional or normal exit and entrance openings merely by raising and lowering the main door panels with the mechanism provided, without speciiic attention to the auxiliary door panels, and these auxiliary panels are swung open to enlarge the access openings only when oversize articles are to be cleansed in the machine.

Another feature of the invention resides in an arrangement for opening the previously described auxiliary door panels automatically each time they are raised, and also for assuring that they are automatically and properly closed as the doors are lowered. A suitable arrangement of this kind is shown in FIGS. l6-18, wherein only those portions of the main and auxiliary door panels and adjacent parts are illustrated. Reference numerals in the three hundred series are used to designate like or similar parts to those previously described.

Thus, the `main door panel 330 has a hinge connection 337 with auxiliary door panel 335 such that the two panels raise and lower simultaneously, while the auxiliary panel can hinge outwardly, particularly as shown in FIG. 17 to provide the enlarged access opening to the chamber of the machine. The automatic control apparatus includes an arm 340 fixed to the interior of door panel 335, and offset to extend around the hinge connection in the closed position, as shown in FIG. 16. At the inner end of arm 340 there is a counterweight 342, and this structure can be duplicated at both sides of the auxiliary door panel if desired. In any event, the total mass of counterweight is selected to be slightly less than the mass of the auxiliary door panel 335. Thus, while the counterweight substantially balances the auxiliary door panel, it is not quite effective to cause swinging movement of the auxiliary panel independent of additional guiding mechanism, but it docs function to minimize the operating force required by such guide mechanism.

The guide and control mechanism for the auxiliary door panel is in the form of a curved double sided track 345 secured to a wall of the machine, for example to the back wall 320 as shown. A roller 347 on arm 340 engages within the track, and thus determines the swinging motion of lever 340 as the auxiliary door panel is raised and lowered. When it is raised, the roller follows the curved track 345 and the auxiliary panel 335 automatically swings open. As the doors are lowered, the roller and track cooperate to cause a closing swinging motion of the auxiliary door panel, and the track includes an extending straight section 343 which contains the roller as the door is lowered, and maintains the auxiliary panel flush -against the guide tracks for the main door, assuring that the lower edge of the auxiliary panel drops within the `base structure 310, as shown in FIG. 16. The track and roller controls can be applied to either or both auxiliary door panels if desired, and they can be duplicated on both sides of the auxiliary door panels if necessary, although in most instances one track and one roller will sufhce to move the counterweighted auxiliary door panel.

The construction shown in FIG. 19 is another `form of auxiliary door panel interlock. This mechanism may if desired include a provision `for opening the auxiliary door panel automatically when the door is raised, or this feature may be omitted and the auxiliary panel then opened only manually.

Since most of the structure is the same as in the construction shown in FIGS. l6-18, the same reference numerals have been applied to identical parts, in order to avoid duplication of the description.

However, in place of the curved doubled-sided track, there is an elongated curved cam rail 350 which engages Ithe roller 347 and assures the closing of the auxiliary door panel 335 when the door is lowered. The counterweight 3412 is an optional feature in the construction. If it is used, as shown, then 'it will be of such mass that it is slightly heavier than the door panel (or if two are used their total mass will overbalance door panel 335). Therefore, when the door is raised `the counterweight will cause roller 347 to follow the rail 350 and the auxiliary panel will open as it -approaches its raised position.

If .the counterweight is omitted, then the auxiliary panel 335 will remain hanging vertically until the operator grasps the handle 352 and opens the auxiliary panel. In either case, the roller 347 and track 350 function as an interlock mechanism, similar to the cam 248 shown in FIGS. l1 and l5, to assure that the door panel 335 is closed against the door tracks before the entire door is completely lowered. This assures proper positioning of the lower edge of door panel 335 as it passes into the base structure.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is `to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended Claims.

What is claimed is:

l. In a dishwashing machine having walls defining a closed chamber and means in said chamber for ilowing cleansing liquid over articles supported therein together with vertically movable doors providing :access to the in- 'terior of said chamber, the combination of counterbalance control mechanism for holding said doors in their raised open position comprising an operating lever including control arms extending adjacent said doors, a pivot mounting for said lever secured to said mach-ine and forming an laxis about which -said control arms can swing, links having pivotal connections at their opposite ends with said door and the adjacent said control arm respectively :for accommodating swinging movement of said arms to linear motion of said doors, compensating spring means anchored at one end to ya fixed point on said mach-ine, a balance link connected to t.e other end of said spring means and having a pivotal connection with said lever located above said laxis in the closed position of said doors, said balance link being rotatable about its said pivotal connection with said lever in a direction opposite to swinging movement of said lever during opening movement of said doors acting to increase ythe effective turning moment exerted by said spring means as said doors open by an amount sufiicient to hold said doors open without interfering with maintaining said doors closed.

2. In a dislrWashing machine having Walls defining a closed chamber and means in -said chamber for flowing cleansing liquid over articles supported therein together with .a vertically movable entrance and exit doors providing access to the interior of said chamber, the combination of counterbalance control mechanism for holding said -doo-rs in raised open position comprising an operating lever including -a control arm extending adjacent to said doors, a pivot mounting 4for said lever secured to said machine and `form-lng an axis about which said con-trol arm can swing, links having separate pivotal connections with said doors and the adjacent said controly arm for accommodating swinging movement of said i arms to linear moti-on of said doors, a drive arm on said lever extending from said pivot mounting a substantially lesser -distance than said control arms and outwardly `from said axis in the `opposite direction from said arms, ya compensating means mounted at the rear of said machine, and balance link means connected to said compensating means and having a pivotal connection `with said drive arm, said balance link means and said compensating means having such dimensional relation to said pivot mounting rand said drive arm that the effective turning moment produced by said compensating lmeans in the closed position of said doors is sufficiently less than in the open position ot said doors that said compensating means will function to -hold said doors in open position and ineflective lto move said doors from closed position without the application of an external force to said control mechanism.

3. In a dishwashing machine having Wall means defining a chamber and spray means for flowing cleansing liquid over article-s supported in said chamber, ent-rance and exit doors on said chamber through which the articles are loaded and unloaded, means mounting said doorsy for vertical opening and closing movement, contro-l mechanism for said doors including a common operating lever having control arms extending adjacent each of said doors, a pivot mounting for said lever secured to said wall means and `forming an axis about which said lever swings during operation of said control mechanism, link means pivotal-ly connected to each of -said doors and to the respective adjacent control arms yfor accommodating swinging movement `of said arms to linear opening and closing motion of said doors, compensating spring means anchored to a fixed point on said machine, drive arm means fixed'to said lever and extending therefrom in the opposite direction from said pivot mounting with respect to said control arms, and vbalance linkage connected to said spring means and having a pivotal'connection with said drive arm means such that the force exerted by spring means tend-ing to open -s'aid doors is so`r directed in the closed position of saidV doors as to be insufficient to lift said doors and the force derivedfrom said spring means is sufiiciently greater inthe open position of said doors to `function as a counterbalance holding said doors in their open position.

4. In a dishwashing machine having' means including front and back walls defining a chamber and sjgi'ray-v means for flowing cleansing liquid over articles supported in said chamber, entrancel and exit doors on opposite sides of said chamber through which the articles are loaded and unloaded, means mount-ing said doors for` vertical opening and closing movement, control mechanism for said doors including a generally U-shalped operating lever havinga central portion and control arms projecting `along said doors and terminating adjacent to each of said doors, a pivot mounting for said lever on said machine forming an axis extending along said back wall about which said armsk and -said centralportion swing in opposite vertical directions during operation of said control mechanism, link means pivotallyv connected t`o` each of said doors and to the respective adjacent control arms for accommodating swinging movement of said arms' to linear motion of said doors, a pair of compensating springs anchored to xed points on said machine, and balance linkage connected to each of said springs and having pivotal connections with said central portion of said lever such that the force exerted by said springs on said lever in the closed position of said doors is in'- sufiicient to lift said doors and said balance linkage is pivoted relative to said central portion of -said lever such that the force i-s directed in the open position oi said `doors to operate as a sufiicient counterbalance holding said doors in their open position.

5. In a dishwashing machine having means including a back wall and a iixed side Wall defining a chamber adapted for placement in :a corner and spray means for flowing cleansing liquid 1over articles Vsupported in said chamber, entrance and exit doors on the other adjacent'l sides of said chamber through which thel articles are"v loaded `and unloaded, means mounting said doors for Vertical opening and closing movement, control mech- `anism for said doors including a common operating'lever having a central portion and control arms extending around said back wall and ixed side wall and terminating adjacent each of said doors, a pivot mounting for said lever secured to said back wall and fixed side Wall and forming an axis about which said arms and central portion `swing in opposite directions during operation ofi said control mechanism, link means pivotally connected to each of said doors and to the respective adjacentv control varms for accommodating swinging movement of said arms to linear motion of said doors, and counterbalance means operatively connected to said centralportion of said lever for counterbalancing said doors.

6. In a dishwashing machine having means includingl a back wall and a fixed side wall defining a chamber adapted for placement in ya corner and spray means for flowing cleansing liquid over articles supported in said chamber, entrance and exit doors on the other adjacentv sides of said chamber through which the articles are" said lever secured to said back wall and fixed side wallV and forming an vaxis yabout which said arms and'central portion swing in opposite directions during operationy of said control mechanism, link means pivotallyr connected'- to each of said doors and to the respective adjacent control arms for accommodating swinging movement of said arms to linear motion of said doors, counterbalance means mounted along said back wall and providing a downward acting force at the rear of said machine, and a balance link connected to said counterbalance means and having a pivotal connection with said central portion of said lever such that the force exerted by said counterbalance means on said lever in the closed position of said doors is insufficient to lift said doors and is increased in the open position of said doors sufiiciently to operate as a counter balance holding said doors in their open position.

7. In a dishwashing machine having wall means defining a chamber and spray means for iiowing cleansing liquid over articles supported in said chamber, main entrance and exit doors on said chamber through which the articles are loaded and unloaded, means mounting said doors for vertical opening and closing movement, control mechanism for said doors including a common operating lever having control arms extending adjacent each of said doors, a pivot mounting for said lever secured to said wall means and forming an axis at the rear of the machine about which said lever swings during operation of said control mechanism, link means pivotally connected to each of said doors and to the respective adjacent control arms for accommodating swinging movement of said arms to linear motion of said doors, spring means anchored to a fixed point on said machine, balance linkage connected to said spring means and having a pivotal connection with said lever such that the force exerted by said spring means tending to open said doors is so directed in the closed position of said doors as to be insufiicient ot lift said doors and the force derived from said spring means is sufiiciently greater in the open position of said doors to function as a counterbalance holding said doors in their open position, each of said main doors including an auxiliary door panel hinged to the lower edge thereof and forming an effective part of the door mechanism for enclosing said chamber, and said auxiliary door panels having means for effecting movement thereof to raised positions providing enlarged yaccess openings for passage of oversize articles into and out of said chamber.

8. In a dishwashing machine having walls defining a chamber and spray means for flowing cleansing liquid over articles supported in said chamber, main entrance and exit doors on said chamber through which the articles are loaded and unloaded, means mounting said doors for vertical opening and closing movement, control mechanism for said doors including a common operating lever having control arms extending adjacent to each of said doors, a pivot mounting for said lever secured to said wall means and forming an axis about which said lever swings during operation of said control mechanism, link means pivotally connected to each of said doors and to the respective adjacent control arms for accommodating swinging movement of said arm to linear motion of said doors, spring means anchored to a fixed point on said machine, balance linkage connected to said spring means and having a pivotal connection with said lever such that the force exerted lby said spring means tending to open said doors is so directed in the closed position of said doors as to be insufhcient to lift said doors and the force derived from said spring means is sufiiciently `greater in the open position of said doors to function as a counterbalance holding said doors in their opeu position, each of said main doors having an auxiliary door panel hinged to the lower edge thereof and forming an effective part of the door mechanism for enclosing said chamber, said auxiliary door panels having means for effecting movement thereof to raised positions providing enlarged access openings for passage of oversize articles into and out of said chamber, and interlock mechanism on said auxiliary door panels functioning in response to actuation of said control mechanism to move said auxiliary door panels to a closed position prior to full closing Iof said main doors.

9. In a dishwashing machine having means defining a chamber and spray means for owing cleansing liquid over articles supported in said chamber, an access door arranged for vertical movement on said chamber providing access to the interior thereof, said door being divided into a main door panel and an auxiliary door panel pivotally mounted on the lower edge of said main door panel, means supporting said door for simultaneous vertical movement of said door panels between `open and closed positions, said pivot mounting of said auxiliary door panel providing for further opening movement thereof to enlarge the access opening for passage of oversize articles therethrough, means for raising and lowering said auxiliary door panel with respect to said main door panel, and interlock mechanism acting on said auxiliary door panel in response to closing movement of said main door panel to assure alignment of yboth said door panels prior to complete closing thereof.

l0. In a dishwashing machine having means defining a chamber and spray means for flowing cleansing liquid over articles supported in said chamber, an access door arranged for vertical movement on said chamber providing access to the interior thereof, said door #being divided into a main door panel and an auxiliary door panel pivotally mounted on the lower edge of said main door panel, means supporting said door for simultaneous vertical movement of said door panels between open and closed positions, said pivot mounting of said auxiliary door panel providing for further opening movement thereof to enlarge the access opening for passage of oversize articles therethrough, means for raising and lowering said auxiliary door panel with respect to said main door panel, and automatic control mechanism connected to open and close said auxiliary door panels with a hinged movement relative to said main door panel during opening and closing movement of said main door panel.

ll. In combination with a dishwashing machine having a tank, means forming a four-sided washing chamber over said tank including a back wall, another normally closed wall, and track means defining entrance and exit openings through the other two walls into said chamber, entrance and exit `doors movable vertically in said track means providing for loading and unloading of articles into and out of said chamber, and spray means in said chamber for iiowing cleansing liquid over` articles supported therein when said doors are in closed position; control mechanism for raising and lowering said doors simultaneously and for holding said doors in their raised open position including a unitary operating `lever extending around the back of said chamber having control arms extending adjacent each of said doors and terminating adjacent the respective said doors, means forming a pivot mounting for said lever defining a horizontal pivot axis for said lever, link means pivotally connected to each of said doors and to the respective adjacent control arm for accommodating swinging movement of said lever and said arms to vertical linear motion of said doors, drive arm means formed as a fixed part of said operating lever and extending outwardly on the opposite side of said axis from said arms to rotate with said lever during openmg and closing movements of said doors. counterbalance means extending along said back wall of said machine and providing an essentially constant counterbalance force, and rbalance linkage connected at one end to said counterbalance means and having a pivotal connection at its other end to said drive arm means, said pivotal connection being located above said pivot forming means such that the turning moment exerted Iby said counterbalance means through said balance linkage on said operating lever is insufcient to lift said doors from their lowered closed position and increases as said doors are opened by an amount sufiicient to enable said counterbalance means to retain said doors in their raised open 75 position.

12. In combination with a dishwashing machine having a tank, means including a back wall, a front wall and a top mounted over said -tank dening a washing chamber, spray means in said chamber for owing cleansing liquid over articles supported in said chamber, entrance and exit doors on the other opposite sides of said chamber through which articles are loaded Iand unloaded, and means mounting said doors for linear vertical opening and closing movement; control mechanism Afor said doors including a common generally U-shaped operating lever having a central portion extending across said back wall and having control arms extending adjacent each of said doors terminating short of said front wall, means -forming a piv-ot mounting for said lever defining a horizontal pivot axis parallel to said back wall about which said Iarms swing during operation `of said control mechanism, link means pivotally connected to each of said doors and to the respective adjacent control arm kfor accommodating swinging movement of said arms to vertical linear motion of said doors, drive arm means formed as a iixed part of said operating lever and extending outwardly on 4the opposite side of said axis from said arms to rotate with said lever during `opening and closing movements of said doors, counterbalance means extending along said back wall of said machine for providing an essentially constant counterbalance force, :and balance linkage connected between said counterbalance means and said drive arm means, said balance linkage and said drive arm means being so arranged with respect to said pivot means and the axis formed thereby that the turning moment exerted by said counterbaJ-ance means on said operating lever is insuliicient to lift said doors from their closed position and increases as said doors are opened by an amount suicient to enable said counterbalance means to hold said doors in their open position.

13. In combination with a dishwashing machine having a tank, means forming a four-sided washing chamber over said tank including a back wall, another normally closed wall, and track means defining entrance and exit openings into said chamber, entrance and exit doors movliquid over articles supported therein when said doors are in closed position; control mechanism for raising and lowering said doors simultaneously and for holding said doors in their raised open position including a unitary oper-ating lever having control arms extending adjacent each of said doors and terminating more adjacent the respective said doors to form handles for grasping by an operator adjacent either said door, means forming a pivot mounting for said lever defining a horizontal pivot axis for said lever, link means pivotally connected to each of said `doors and to the respective adjacent control arm for accommodating swinging movement of said arms to vertical linear motion of said doors, dn've arm means formed as a fixed part of said operating lever and extending outwardly on the opposite side of said axis from said iarms to rotate with said lever during opening and closing movements of said doors, counterbalance means extending along said back Wall of said machine fand -providing an essentially constant counterbalance force, land balance linkage connected at one end to said counterbalance means fand having a pivotal connection at its other end to said drive arm means, said balance linkage and said drive larm means and said pivotal connection therebetween being arranged with respect to said pivot forming means such that the turning moment exerted by said counterbalance means through said balance linkage on said operating lever is insuicient to lift said ydoors from their lowered 'closed position and increases as said doors are opened by an amount suiiicient to enable said counterbalance means to retain said `doors in their raised open position.

References Cited in the le of this patent UNITED STATES PATENTS Re. 22,206 Parsons Oct. 20, 1942 1,067,084 Wandtke July 8, 1913 1,073,554 Zeller Sept. 16, 1913 1,366,072 Hall Jan. 18, 1921 1,539,170 Eddison May 26, 1925 FOREIGN PATENTS 544,096 Belgium Ian. 14, 1956 

